In one aspect, the present invention relates to compounds which are potent and specific inhibitors of thrombin. In another aspect, the present invention relates to novel peptide aldehydes, their pharmaceutically acceptable salts, and pharmaceutically acceptable compositions thereof which are useful as potent and specific inhibitors of blood coagulation in vitro and in vivo in mammals. In yet another aspect, the invention relates to methods of using these inhibitors as therapeutic agents for disease states in mammals characterized by abnormal thrombosis.
Normal hemostasis is the result of a complex balance between the processes of clot formation (blood coagulation) and clot dissolution (fibrinolysis). The complex interactions between blood cells, specific plasma proteins and the vascular surface, maintain the fluidity of blood unless injury and blood loss occur.
Blood coagulation is the culmination of a series of amplified reactions in which several specific zymogens of serine proteases in plasma are activated by limited proteolysis. Nemerson, Y. and Nossel, H. L., Ann. Rev. Med., 33: 479 (1982). This series of reactions results in the formation of an insoluble fibrin matrix which is required for the stabilization of the primary hemostatic plug. The interaction and propagation of the activation reactions occurs through the extrinsic and intrinsic pathways of coagulation.
These pathways are highly inter-dependent and converge in the formation of the serine protease, Factor Xa. Factor Xa catalyzes the penultimate step in the blood coagulation cascade which is the formation of the serine protease thrombin. This step occurs following the assembly of the prothrombinase complex which is composed of factor Xa, the non-enzymatic co-factor Va and the substrate prothrombin assembled on the surface of adhered, activated platelets or systemically circulating membranous microparticles.
Proteolytic activation of zymogen factor X to its catalytically active form, factor Xa, can occur by either the intrinsic or extrinsic coagulation pathways.
The intrinsic pathway is referred to as xe2x80x9cintrinsicxe2x80x9d because everything needed for clotting is in the blood.
Saito, H., xe2x80x9cNormal Hemostatic Mechanismsxe2x80x9d, Disorders of Hemostasis, pp. 27-29, Grune and Stratton, Inc. (O. D. Ratnoff, M. D. and C. D. Forbes, M. D. edit. 1984). This pathway is comprised of the zymogen serine proteases, factors IX and XI, and the non-enzymatic co-factor, factor VIII. The initiation of the intrinsic pathway results in the activation of factor XI to XIa. Factor XIa catalyzes the activation of factor IX to factor IXa which in combination with the activated form of factor VIII on an appropriate phospholipid surface, results in the formation of the tenase complex. This complex also catalyzes the formation of the serine protease, factor Xa, from its zymogen, factor X which subsequently results in clot formation.
The extrinsic pathway is referred to as xe2x80x9cextrinsicxe2x80x9d because the tissue factor which binds to and facilitates the activation of factor VII comes from outside the blood. Saito, Id. The major components of this pathway are the zymogen serine protease, factor VII, and the membrane bound protein, tissue factor. The latter serves as the requisite non-enzymatic co-factor for this enzyme. The initiation of this pathway is thought to be an autocatalytic event resulting from the activation of zymogen factor VII by trace levels of activated factor VII (factor VIIa), both of which are bound to newly exposed tissue factor on membrane surfaces at sites of vascular damage. The factor VIIa/tissue factor complex directly catalyzes the formation of the serine protease, factor Xa, from its zymogen, factor X. Exposure of blood to injured tissue initiates blood clotting by the extrinsic pathway.
The formation of thrombin is catalyzed by factor Xa following the assembly of the catalytic prothrombinase complex as reviewed by Mann, K. G. et al., xe2x80x9cSurface-Dependent Reactions of the Vitamin K-Dependent Enzyme Complexesxe2x80x9d, Blood, 76: 1-16 (1990). This complex is composed of factor Xa, the non-enzymatic co-factor Va and the substrate prothrombin all assembled on an appropriate phospholipid surface. The requirement of a macromolecular complex for efficient catalysis results in the protection of factor Xa from natural anticoagulant mechanisms such as heparin-antithrombin III mediated inhibition. Teite, J. M. and Rosenberg, R. D., xe2x80x9cProtection of Factor Xa from neutralization by the heparin-antithrombin complexxe2x80x9d, J. Clin. Invest., 71: 1383-1391(1983). In addition, sequestration of factor Xa in the prothrombinase complex also renders it resistant to inhibition by exogenous heparin therapy which also requires antithrombin III to elicit its anticoagulant effect.
Thrombin is the primary mediator of thrombus formation. Thrombin acts directly to cause formation of insoluble fibrin from circulating fibrinogen. In addition, thrombin activates the zymogen factor XIII to the active transglutaminase factor XIIIa which acts to covalently stabilize the growing thrombus by crosslinking the fibrin strands. Lorand, L. and Konishi, K., Arch. Biochem. Biophys., 105: 58 (1964). Beyond its direct role in the formation and stabilization of fibrin rich clots, the enzyme has been reported to have profound bioregulatory effects on a number of cellular components within the vasculature and blood. Shuman, M. A., Ann. NY Acad. Sci., 405: 349 (1986).
It is believed that thrombin is the most potent agonist of platelet activation, and it has been demonstrated to be the primary pathophysiologic-mediator of platelet-dependent arterial thrombus formation. Edit, J. F. et al., J. Clin. Invest., 84: 18 (1989). Thrombin-mediated platelet activation leads to ligand-induced inter-platelet aggregation principally due to the bivalent interactions between adhesive ligands such as fibrinogen and fibronectin with platelet integrin receptors such as glycoprotein IIb/IIIa which assume their active conformation following thrombin activation. Berndt, M. C. and Phillips, D. R., Platelets in Biology and Pathology, pp 43-74, Elsevier/North Holland Biomedical Press (Gordon, J. L. edit. 1981). Thrombin-activated platelets can also support further thrombin production through the assembly of new prothrombinase and tenase (factor IXa, factor VIIIa and factor X) catalytic complexes on the membrane surface of intact activated platelets and platelet-derived microparticles, following thrombin-mediated activation of the non-enzymatic cofactors V and VIII, respectively. Tans, G. et al., Blood, 77: 2641 (1991). This positive feedback process results in the local generation of large concentrations of thrombin within the vicinity of the thrombus which supports further thrombus growth and extension. Mann, K. G. et al., Blood, 76: 1 (1990).
In contrast to its prothrombotic effects, thrombin has been shown to influence other aspects of hemostasis. These include its effect as an important physiological anticoagulant. The anticoagulant effect of thrombin is expressed following binding of thrombin to the endothelial cell membrane glycoprotein, thrombomodulin. This is thought to result in an alteration of the substrate specificity of thrombin thereby allowing it to recognize and proteolytically activate circulating protein C to give activated protein C (aPC). Musci, G. et al., Biochemistry, 27: 769 (1988). aPC is a serine protease which selectively inactivates the non-enzymatic co-factors Va and VIIIa resulting in a down-regulation of thrombin formation by the prothrombinase and tenase catalytic complexes, respectively. Esmon, C. T., Science, 235: 1348 (1987). The activation of protein C by thrombin in the absence of thrombomodulin is poor.
Thrombin has also been shown to be a potent direct mitogen for a number of cell types, including cells of mesenchymal origin such as vascular smooth muscle cells. Chen, L. B. and Buchanan, J. M., Proc. Natl. Acad. Sci. USA, 72: 131 (1975). The direct interaction of thrombin with vascular smooth muscle also results in vasoconstriction. Walz, D. A. et al., Proc. Soc. Expl. Biol. Med., 180: 518 (1985). Thrombin acts as a direct secretagogue inducing the release of a number of bioactive substances from vascular endothelial cells including tissue plasminogen activator. Levin, E. G. et al., Thromb. Haemost., 56: 115 (1986). In addition to these direct effects on vascular cells, the enzyme can indirectly elaborate potent mitogenic activity on vascular smooth muscle cells by the release of several potent growth factors (e.g., platelet-derived growth factor and epidermal growth factor) from platelet a-granules following thrombin-induced activation. Ross, R., N. Engl. J. Med., 314: 408 (1986).
Many significant disease states are related to abnormal hemostasis. With respect to the coronary arterial vasculature, abnormal thrombus formation due to the rupture of an established atherosclerotic plaque is the major cause of acute myocardial infarction and unstable angina. Moreover, treatment of an occlusive coronary thrombus by either thrombolytic therapy or percutaneous transluminal coronary angioplasty (PTCA) is often accompanied by an acute thrombotic reclosure of the affected vessel which requires immediate resolution. With respect to the venous vasculature, a high percentage of patients undergoing major surgery in the lower extremities or the abdominal area suffer from thrombus formation in the venous vasculature which can result in reduced blood flow to the affected extremity and a predisposition to pulmonary embolism. Disseminated intravascular coagulopathy commonly occurs within both vascular systems during septic shock, certain viral infections and cancer and is characterized by the rapid consumption of coagulation factors and systemic coagulation which results in the formation of life-threatening thrombi occurring throughout the vasculature leading to widespread organ failure.
Pathogenic thrombosis in the arterial vasculature is a major clinical concern in today""s medicine. It is the leading cause of acute myocardial infarction which is one of the leading causes of death in the western world. Recurrent arterial thrombosis also remains one of the leading causes of failure following enzymatic or mechanical recanalization of occluded coronary vessels using thrombolytic agents or percutaneous transluminal coronary angioplasty (PTCA), respectively. Ross, A. M., Thrombosis in Cardiovascular Disorder, p. 327, W. B. Saunders Co. (Fuster, V. and Verstraete, M. edit. 1991); Califf, R. M. and Willerson, J. T., Id. at p 389. In contrast to thrombotic events in the venous vasculature, arterial thrombosis is the result of a complex interaction between fibrin formation resulting from the blood coagulation cascade and cellular components, particularly platelets, which make up a large percentage of arterial thrombi. Heparin, the most widely used clinical anticoagulant administered i.v., has not been shown to be universally effective in the treatment or prevention of acute arterial thrombosis or rethrombosis. Prins, M. H. and Hirsh, J., J. Am. Coll. Cardiol., 67: 3A (1991).
Besides the unpredictable, recurrent thrombotic reocclusion which commonly occurs following PTCA, a profound restenosis of the recanalized vessel occurs in 30 to 40% of patients 1 to 6 months following this procedure. Califf, R. M. et al., J. Am. Coll. Cardiol., 17: 2B (1991). These patients require further treatment with either a repeat PTCA or coronary artery bypass surgery to relieve the newly formed stenosis. Restenosis of a mechanically damaged vessel is not a thrombotic process but instead is the result of a hyperproliferative response in the surrounding smooth muscle cells which over time results in a decreased luminal diameter of the affected vessel due to increased muscle mass. Id. As for arterial thrombosis, there is currently no effective pharmacologic treatment for the prevention of vascular restenosis following mechanical recanalization.
The need for safe and effective therapeutic anticoagulants has in one aspect focused on the role of the serine protease thrombin in blood coagulation.
Most preferred natural substrates for thrombin are reported to contain an uncharged amino acid in the P3 recognition subsite. For example, the thrombin cleavage site on the Axcex1 chain of fibrinogen, which is the primary physiological substrate for thrombin, is reported to contain a glycine residue in this position while the cleavage site on the Bxcex2 chain contains a serine, as shown below: 
Peptidyl derivatives having an uncharged residue in the P3 position are said to bind to the active site of thrombin and thereby inhibit the conversion of fibrinogen to fibrin and inhibit cellular activation. These derivatives have either an aldehyde, chloromethyl ketone or boronic acid functionality associated with the P1 amino acid. For example, substrate-like peptidyl derivatives such as D-phenylalanyl-prolyl-argininal (D-Phe-Pro-Arg-al), D-phenylalanyl-prolyl-arginine-chloromethyl ketone (P-PACK) and acetyl-D-phenylalanyl-prolyl-boroarginine (Ac-(D-Phe)-Pro-boroArg) have been reported to inhibit thrombin by directly binding to the active site of the enzyme. Bajusz, S., Symposia Biologica Hungarica, 25: 277 (1984), Bajusz, S. et al, J. Med. Chem., 33: 1729 (1990) and Bajusz, S. et al., Int. J. Peptide Protein Res. 12: 217 (1970); Kettner, C. and Shaw, E., Methods Enzymol., 80: 826 (1987), Kettner, C. et al., EP 293,881 (published Dec. 7, 1988), Kettner, C., et al., J. Biol. Chem., 265: 18209 (1990). These molecules have been reported to be potent anticoagulants in the prevention of platelet-rich arterial thrombosis. Kelly, A. B. et al., Thromb. Haemostas., 65: 736 at abstract 257 (1991). Other peptidyl aldehydes have been proposed or reported as inhibitors of thrombin. Bey, P. et al., EP 363,284 (published Apr. 11, 1990) and Balasubramanian, N. et al., EP 526,877 (published Feb. 10, 1993).
Peptidyl compounds which are said to be active site inhibitors of thrombin but which differ in structure from those containing a uncharged amino acid in the P3 recognition subsite have been reported.
The compound, Argatroban (also called 2R,4R-4-methyl-1-[N-2-(3-methyl-1,2,3,4-tetrahydro-8-quinolinesulfonyl)-L-argininal]-2-piperdinecarboxylic acid), is also reported to bind directly to the active site of thrombin and has been thought to be the most potent and selective compound in the class of non-peptidyl inhibitors of this enzyme. Okamoto, S. et al., Biochem. Biophys. Res. Commun., 101: 440 (1981). Argatroban has been reported to be a potent antithrombotic agent in several experimental models of acute arterial thrombosis. Jang, I. K. et al., in both Circulation, 81: 219 (1990) and Circ. Res., 67: 1552 (1990).
Peptidyl compounds which are said to be inhibitors of thrombin and whose mode of action is thought to be by binding to both the active site and another site on the enzyme have been reported. Hirudin and certain peptidyl derivatives of hirudin have been reported to inhibit both conversion of fibrinogen to fibrin and platelet activation by binding to either both the active site and exo site, or the exo site only, of thrombin. Markwardt, F., Thromb. Haemostas., 66: 141 (1991). Hirudin is reported to be a amino acid polypeptide originally isolated from leech salivary gland extracts. It is said to be one of the most potent inhibitors of thrombin known. Marki, W. E. and Wallis, R. B., Thromb. Haemostas., 64: 344 (1990). It has been reported to inhibit thrombin by binding to both its anion-binding exo-site and to its catalytic active site which are distinct and physically distant from each other. Rydel, T. J. et al., Science, 249:277 (1990). Hirudin has been reported to be a potent antithrombotic agent in vivo. Markwardt, F. et al., Pharmazie, 43: 202 (1988); Kelly, A. B. et al., Blood, 77: 1 (1991). In addition to its antithrombotic effects, hirudin has been reported to also effectively inhibit smooth muscle proliferation and the associated restenosis following mechanical damage to a atherosclerotic rabbit femoral artery. Sarembock, I. J. et al., Circulation, 84: 232 (1991).
Hirugen has been reported to be a peptide derived from the anionic carboxy-terminus of hirudin. It is reported to bind only to the anion binding exo-site of thrombin and thereby inhibit the formation of fibrin but not the catalytic turnover of small synthetic substrates which have access to the unblocked active site of the enzyme. Maraganore, J. M. et al., J. Biol. Chem., 264: 8692 (1989); Naski, M. C. et al., J. Biol. Chem., 265: 13484 (1990). Based on x-ray crystallographic analysis, it has been reported that the region of hirudin represented by hirugen binds directly to the exo site of thrombin. Skrzypczak-Jankun, E. et al., Thromb. Haemostas., 65: 830 at abstract 507 (1991). Moreover, the binding of hirugen has also been reported to enhance the catalytic turnover of certain small synthetic substrates by thrombin, indicating that a conformational change in the enzyme active site may accompany occupancy of the exo-site. Liu, L. W. et al., J. Biol. Chem, 266:16977 (1991). Hirugen also is reported to block thrombin-mediated platelet aggregation. Jakubowski, J. A. and Maraganore, J. M., Blood, 75: 399 (1990).
A group of synthetic chimeric molecules comprised of a hirugen-like sequence linked by a glycine-spacer region to the peptide, D-phenylalanyl-prolyl-arginine, which is based on a preferred substrate recognition site for thrombin, has been termed to be hirulog. Maraganore et al., U.S. Pat. No. 5,196,404 (Mar. 23, 1993). The hirugen-like sequence is said to be linked to this peptide through the C-terminal end of the peptide. Maraganone, J. M. et al., Biochemistry, 29: 7095 (1990). The hirulogs have been reported to be an effective antithrombotic agents in preventing both fibrin-rich and platelet-rich thrombosis. Maraganone, J. M. et al., Thromb. Haemostas., 65: 651 at abstract 17 (1991).
Certain benzamidines have been reported to inhibit thrombin though non-selectively. 4-amidinophenylpyruvic acid (APPA) has been reported to be a thrombin inhibitor with low toxicity and favorable pharmacokinetics. However, this compound was reported to be non-selective, inhibiting trypsin, plasmin and kallikrein. Markwardt et al., Thromb. Res., 1:243-52 (1972). Other benzamidine-derived structures which have been reported to inhibit thrombin include the cylic amides of Na-substituted 4-amidinophenylalanine and 2-amino-5-(4-amidinophenyl)-1-valeric acid. The inhibitory constant displayed by these compounds was reported to be in the micromolar range. Markwardt et al., Thromb. Res., 17:425-31 (1980). Moreover, derivatives of 4-amidinophenylalanine whose a-amino group is linked to the arylsulfonyl residue via an w-aminoalkylcarboxylic acid as spacer have also been assessed for their inhibitory effect. Among these Na-(2-naphthylsulphonylglycyl)-4-amidino-phenylalanine piperidide (a-NAPAP) has been reported to possess an affinity for thrombin (Ki=6xc3x9710xe2x88x929 M). Banner et al., J. Biol. Chem., 266:20085 (1991) and Sturzebecher et al., Thromb. Res., 29:635-42 (1983).
Certain bis-benzamidines have been reported to inhibit thrombin. The antithrombin activity of bis-benzamidines was reported to increase with the length and bulkiness of the central chain. However, these compounds were reported to be generally toxic in the micromolar range where they are also inhibitory. Geratz et al., Thromb. Diath. Haemorrh., 29:154-67 (1973); Geratz et al., J. Med. Chem., 16:970-5 (1973); Geratz et al., J. Med. Chem., 19:634-9 (1976); Walsmann et al., Acta Biol. Med. Germ., 35:K1-8 (1976); and Hauptmann et al., Acta Biol. Med. Germ., 35:635-44 (1976).
Certain amidino-bearing aromatic ring structures such a beta-naphthamidines have been reported to possess modest antithrombin and anticoagulant activity. This class of compounds include the non-selective 6-amidino-2-naphthyl-4-guanidinobenzoate dimethanesulfonate (FUT 175). Fuji et al., Biochim. Biophys. Acta, 661:342-5 (1981); and Hitomi et al., Haemostasis, 15:164-8 (1985).
Certain phenylguanidines have been reported to inhibit thrombin. Derivatives of 4-guanidinophenylalanine with inhibitory constants in the micromolar range have been reported to inhibit thrombin. This class includes the Na-tosylated and dansylated 4-guanidino phenylalanine piperidides. Claeson et al., Thromb. Haemostas., 50:53 (1983). Another compound, [ethyl p-(6-guanidinohexanoyloxy)benzoate]methane sulfonate (FOY) was reported to be a non-selective competitive inhibitor of thrombin. Ohno et al., Thromb. Res., 19:579-588 (1980).
The present invention is directed to novel peptide aldehyde compounds having arginine or arginine mimics at P1 and pyridone, pyrimidone, or uracil groups as part of the peptide backbone. These compounds are potent inhibitors of thrombin in vivo and in vitro.
Thus, in one aspect, the present invention is directed to compounds of the formula: 
wherein
(a) X is selected from the group consisting of xe2x80x94S(O)2xe2x80x94, xe2x80x94NHxe2x80x94S(O)2xe2x80x94, xe2x80x94N(Rxe2x80x2)xe2x80x94S(O)2xe2x80x94, xe2x80x94C(xe2x95x90O)xe2x80x94, xe2x80x94OC(xe2x95x90O)xe2x80x94, xe2x80x94NHxe2x80x94C(xe2x95x90O)xe2x80x94, and a direct link, wherein Rxe2x80x2 is alkyl of 1 to about 4 carbon atoms;
(b) R1 is selected from the group consisting of:
(1) alkyl of 1 to about 12 carbon atoms,
(2) alkyl of 1 to about 3 carbon atoms substituted with cyclic alkyl of about 5 to about 8 carbon atoms,
(3) alkenyl of about 3 to about 6 carbon atoms which is optionally substituted with cyclic alkyl of about 5 to about 8 carbon atoms,
(4) aryl of about 4 to about 14 carbon atoms which is optionally mono-substituted with Y1 or optionally di-substituted with Y1 and Y2,
(5) aralkyl of about 5 to about 15 carbon atoms which is optionally mono-substituted in the aryl ring with Y1 or optionally di-substituted in the aryl ring with Y1 and Y2,
(6) aralkenyl of about 6 to about 15 carbon atoms which is optionally mono-substituted in the aryl ring with Y1 or optionally di-substituted in the aryl ring with Y1 and Y2, 
(11) perfluoroalkyl of 1 to about 12 carbon atoms,
(12) perfluoroaryl of about 6 to about 14 carbon atoms,
(13) perfluoroaryl alkyl of about 7 to about 15 carbon atoms, and
(14) hydrogen,
where Y1 and Y2 are independently selected from halogen, xe2x80x94CF3, xe2x80x94CF2CF3, xe2x80x94CH(CF3)2, xe2x80x94COH(CF3)2, cyano, nitro, xe2x80x94C(O)OH, xe2x80x94C(O)OZ1, xe2x80x94Z1, xe2x80x94OZ1, xe2x80x94OH, xe2x80x94P(O)3H2, xe2x80x94P(O)3(Z1)2, tetrazolyl, xe2x80x94S(O)3H and xe2x80x94S(O)mZ1 wherein m is 0, 1 or 2, Z1 is alkyl of 1 to about 12 carbon atoms, aryl of about 4 to about 14 carbon atoms and aralkyl of about 5 to about 15 carbon atoms, with the provisos that:
(1) when Y1 is halogen, then Y2 is hydrogen or halogen;
(2) when Y1 is xe2x80x94C(O)OH, then Y2 is hydrogen, xe2x80x94OH or xe2x80x94C(O)OH;
(3) when Y1 is xe2x80x94C(O)OZ1, then Y2 is hydrogen, xe2x80x94OH or xe2x80x94C(O)OZ1;
(4) when Y1 is xe2x80x94Z1, then Y2 is hydrogen, xe2x80x94OH or xe2x80x94Z1;
(5) when Y1 is xe2x80x94CF3, then Y2 is hydrogen, xe2x80x94OH or xe2x80x94CF3;
(6) when Y1 is xe2x80x94OZ1, then Y2 is hydrogen, xe2x80x94OH or xe2x80x94OZ1;
(7) when Y1 is xe2x80x94OH, then Y2 is hydrogen, xe2x80x94OH, xe2x80x94C(O)OH, xe2x80x94C(O)OZ1, xe2x80x94CF3, xe2x80x94S(O)3H, or xe2x80x94S(O)mZ1; and
(8) when Y1 is cyano, nitro, xe2x80x94P(O)3H2, xe2x80x94P(O)3(Z1)2, or tetrazolyl, then Y2 is hydrogen;
(c) R2 is selected from the group consisting of 
xe2x80x83where W is nitrogen or carbon; and
(d) Het is selected from the group consisting of 
xe2x80x83wherein R3 is hydrogen, alkyl of 1 to about 2 carbon atoms, or cycloalkyl of about 3 carbon atoms, R4 is hydrogen or methyl, and pharmaceutically acceptable salts thereof, with the proviso that when X is other than a direct link R1 is not hydrogen.
Peptidyl arginine aldehydes have been reported to exist in equilibrium structures in aqueous solutions. Bajusz, S., et al., J. Med. Chem., 33: 1729 (1990). These structures, as shown below, include the arginine aldehyde, A, aldehyde hydrate, B, and two amino cyclol forms, C and D. The R group would represent the remainder of a given compound embodied in the present invention. The peptide aldehydes of the present invention include within their definition all the equilibrium forms. 
Among other factors, the present invention is based on our finding that the novel compounds of our invention are active as selective inhibitors of thrombin. In particular, we have found that certain of the preferred compounds of the present invention exhibit advantageous selectivity in that they are very potent inhibitors of thrombin but are inactive or significantly less active, (several orders of magnitude less) in inhibiting plasmin and are significantly less active in inhibiting trypsin. This selectivity for inhibition of thrombin gives these compounds a therapeutic advantage in treating or preventing thrombosis in a mammal suspected of having a condition characterized by abnormal thrombosis.
In another aspect, the present invention is directed to pharmaceutical compositions comprising a therapeutically effective amount of a compound of the present invention and a pharmaceutically acceptable carrier.
In yet another aspect, the present invention is directed to methods of using the compounds and pharmaceutical compositions of the present invention for the prevention of thrombosis in a mammal suspected of having a condition characterized by abnormal thrombosis, comprising administering to said mammal a therapeutically effective amount of a compound of the present invention or pharmaceutical composition comprising such a compound.
In accordance with the present invention and as used herein, the following terms are defined to have following meanings, unless explicitly stated otherwise:
The term xe2x80x9calkylxe2x80x9d refers to saturated aliphatic groups including straight-chain, branched-chain and cyclic groups. Suitable alkyl groups include cyclohexyl and cyclohexylmethyl.
The term xe2x80x9carylxe2x80x9d refers to aromatic groups which have at least one ring having a conjugated pi electron system and includes carbocyclic aryl, heterocyclic aryl and biaryl groups, all of which may be optionally substituted.
The term xe2x80x9ccarbocyclic arylxe2x80x9d refers to aromatic groups wherein the ring atoms on the aromatic ring are carbon atoms. Carbocyclic aryl groups include monocyclic carbocyclic aryl groups and naphthyl groups, all of which may be optionally substituted. Suitable carbocyclic aryl groups include phenyl and naphthyl. Suitable substituted carbocyclic aryl groups include indene and phenyl substituted by one to two substituents such being advantageously lower alkyl, hydroxy, lower alkoxy, lower alkoxycarbonyl, halogen, trifluoromethyl, nitro, and cyano. Substituted naphthyl refers to 1- or 2-naphthyl substituted by lower alkyl, lower alkoxy, or halogen.
The term xe2x80x9cheterocyclic arylxe2x80x9d refers to aryl groups having from 1 to 3 heteroatoms as ring atoms in the aromatic ring and the remainder of the ring atoms are carbon atoms. Suitable heteroatoms include oxygen, sulfur, and nitrogen, and suitable heterocyclic aryls include furanyl, thienyl, pyridyl, pyrrolyl, pyrimidyl, pyrazinyl, imidazolyl, and the like.
The term xe2x80x9cbiarylxe2x80x9d refers to phenyl substituted by carbocyclic or heterocyclic aryl as defined herein, ortho, meta or para to the point of attachment of the phenyl ring, advantageously para.
The term xe2x80x9clowerxe2x80x9d referred to herein in connection with organic radicals or compounds defines such with up to and including 5, preferably up to and including 4 and advantageously one or two carbon atoms. Such groups may be straight chain or branched chain.
The term xe2x80x9calkoxyxe2x80x9d refers to xe2x80x94OR wherein R is alkyl.
The term xe2x80x9calkoxycarbonylxe2x80x9d refers to xe2x80x94C(O)OR wherein R is alkyl.
The term xe2x80x9caralkylxe2x80x9d refers to an alkyl group substituted with an aryl group. Suitable aralkyl groups include benzyl, picolyl, and the like, all of which may be optionally substituted.
The term xe2x80x9cperfluoroalkylxe2x80x9d refers to an alkyl group which has every hydrogen replaced with fluorine.
The term xe2x80x9cperfluoroarylxe2x80x9d refers to an aryl group which has every hydrogen replaced with fluorine.
The term xe2x80x9cperfluoroaryl alkylxe2x80x9d refers an aralkyl group in which every hydrogen on the aryl moiety is replaced with fluorine.
The term xe2x80x9ccycloalkylxe2x80x9d refers to a cyclic alkyl group. Suitable cycloalkyl groups include cyclohexyl.
The term xe2x80x9calkenylxe2x80x9d refers to an unsaturated aliphatic group having at least one double bond.
The term xe2x80x9caralkenylxe2x80x9d refers to an alkenyl group substituted with an aryl group.
The term xe2x80x9camino acidxe2x80x9d refers to both natural, unnatural amino acids in their D and L stereoisomers if their structure allows such stereoisomeric forms, and their analogs. Natural amino acids include alanine (Ala), arginine (Arg), asparagine (Asn), aspartic acid (Asp), cysteine (Cys), glutamine (Gln), glutamic acid (Glu), glycine (Gly), histidine (His), isoleucine (Ile), leucine (Leu), lysine (Lys), methionine (Met), phenylalanine (Phe), proline (Pro), serine (Ser), threonine (Thr), tryptophan (Trp), tyrosine (Tyr) and valine (Val). Unnatural amino acids include, but are not limited to azetidinecarboxylic acid, 2-aminoadipic acid, 3-aminoadipic acid, beta-alanine, aminopropionic acid, 2-aminobutyric acid, 4-aminobutyric acid, 6-aminocaproic acid, 2-aminoheptanoic acid, 2-aminoisobutyric acid, 3-aminoisobutyric acid, 2-aminopimelic acid, 2,4-diaminoisobutyric acid, desmosine, 2,2xe2x80x2-diaminopimelic acid, 2,3-diaminopropionic acid, N-ethylglycine, N-ethylasparagine, hydroxylysine, allo-hydroxylysine, 3-hydroxyproline, 4-hydroxyproline, isodesmosine, allo-isoleucine, N-methylglycine, N-methylisoleucine, N-methylvaline, norvaline, norleucine, ornithine and pipecolic acid. Amino acid analogs include the natural and unnatural amino acids which are chemically blocked, reversibly or irreversibly, or modified on their N-terminal amino group or their side-chain groups, as for example, methionine sulfoxide, methionine sulfone, S-(carboxymethyl)-cysteine, S-(carboxymethyl)-cysteine sulfoxide and S-(carboxymethyl)-cysteine sulfone.
The term xe2x80x9camino acid residuexe2x80x9d refers to radicals having the structure: (1) xe2x80x94C(O)xe2x80x94Rxe2x80x94NHxe2x80x94, wherein R typically is xe2x80x94CH(Rxe2x80x2)xe2x80x94, wherein Rxe2x80x2 is H or a carbon containing substituent; or (2) 
wherein p is 1, 2 or 3 representing the azetidinecarboxylic acid, proline or pipecolic acid residues, respectively.
The term xe2x80x9chalogenxe2x80x9d refers to fluorine, chlorine, bromine and iodine atoms.
The term xe2x80x9cArg-alxe2x80x9d refers to the residue of L-argininal which has the formula: 
xe2x80x9cN-alpha-t-butoxycarbonyl-Ng-nitro-L-argininexe2x80x9d refers to the compound which has the formula: 
In addition, the following abbreviations stand for the following:
xe2x80x9cBocxe2x80x9d refers to t-butoxycarbonyl.
xe2x80x9cBOPxe2x80x9d refers to benzotriazol-1-yl-oxy-tris-(dimethylamino)-phosphonium hexafluorophosphate.
xe2x80x9cBrinexe2x80x9d refers to an aqueous saturated solution of sodium chloride.
xe2x80x9cBzlSO2xe2x80x9d refers to benzylsulfonyl.
xe2x80x9cDCCxe2x80x9d refers to N,Nxe2x80x2-dicyclohexylcarbodiimide.
xe2x80x9cEDCxe2x80x9d refers to 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride salt.
xe2x80x9cHBTUxe2x80x9d refers to 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium hexafluorophosphate.
xe2x80x9cHClxe2x80x9d refers to hydrochloric acid.
xe2x80x9cHOBtxe2x80x9d refers to 1-hydroxybenzotriazole monohydrate.
xe2x80x9cHPLCxe2x80x9d refers to high pressure liquid chromatography.
xe2x80x9c2-PrPenxe2x80x9d refers to 2-propylpentanoyl.
xe2x80x9cLiAlH4xe2x80x9d refers to lithium aluminum hydride.
xe2x80x9cLiAlH2(OEt)2 refers to lithium aluminum dihydride diethoxide.
xe2x80x9cNaOHxe2x80x9d refers to sodium hydroxide.
xe2x80x9cNMMxe2x80x9d refers to N-methylmorpholine.
xe2x80x9cTBTUxe2x80x9d refers to 2-(1H-benzotriazol-1-yl)-1,1,3,3-tetramethyluronium tetrafluoroborate.
xe2x80x9cTHFxe2x80x9d refers to tetrahydrofuran.
xe2x80x9cTLCxe2x80x9d refers to thin layer chromatography.